1. Field of the Invention
The present invention relates to an ignition-timing adjusting system for an internal combustion engine, and more particularly, to a system for realizing the proper advance of the ignition-timing (or spark-timing) of an engine during operation when the engine is cold.
It is well-known that the ignition-timing of a conventional spark-ignition engine should be varied for different operating conditions in order to ensure the most effective and smooth operation. Specifically, in a spark-ignition engine for automobiles, for example, the normal ignition-timing is generally preset so that an effective and smooth operation can be achieved when the engine is idling and is warm. Accordingly, at higher speeds, or under a part-load (or part-open throttle) operating condition or when the engine is cold, the ignition should be advanced.
Particularly, it is well-known that the proper advance of the ignition-timing during operation of a cold engine provides an increase in the out-put power and a large improvement in fuel-consumption, and enhances engine response and performance. Further, there is a decrease in the quantity of harmful constituents contained in the exhaust gas.
2. Description of the Prior Art
The advance of the ignition-timing relating to the engine-speed and/or the engine-load condition is achieved by employing a centrifugal advance mechanism and/or a vacuum advance mechanism, respectively, which are both well-known.
In order to realize said advance of the ignition-timing with relation to the engine-temperature, an electrical advance system is generally used. A conventional electrical system includes two or more sets of breaker points in the distributor, an electrical switch responsive to the engine-temperature, and a relay for selecting one of said sets of breaker points. This system operates electrically in such a manner that any one set of breaker points, which provides the proper ignition-timing advance, is selected according to the engine-temperature.
However, said electrical advance system has many disadvantages. That is, the electrical elements for the selecting of the breaker points are very expensive, and service and maintenance thereof are hard to obtain because adjusting or repairing of two or more sets of breaker points is very difficult and time consuming.